Improvement in steam-boiler furnaces



JOHN T.HANCOGK, OF BOSTON, MASSACHUSETTS.

lMPPtOVEMENT iN STEAMBOILERL FURNAGES.

To all whom it may concern:

Be it known that I, JOHN T. HANCOCK, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Steam-Blowers; andI hereby declare that the following description, taken in connection with the accompanying drawings, hereinafter referred to, forms a full and exact specification of the same, wherein have set forth the nature and principles of my said improvements, whereby my invention may be distinguished from all others of a similar class, together with suc-h parts as I claim and desire to have secured to me by Letters Patent.

The primary object of this invention is the production of a warm, moist, and constant blast for increasing the energy of furnace-fires,

. and for contributing to the perfect combustion and economy of the fuel. Its secondary objects are the ventilation of buildings, ships, and mines and the promoting of the evaporating of liquids.

It has long been known to that portion of the manufacturing community whose business requires the aid of fires of great intensity that with the same amount of natural or arti; icial draft and with equal care in ring there is, at particular times a material diminution in the amount of work usually performed by the same quantity of fuel, arising` from some peculiarity in the air supplied to the re. 1t has also been observed that at such times the presence of .moisture in .limited quantities in the ash-pit has a tendency to cause the iires to burn more clearly, and also for the time to yield a greater relative amount of peat. g rlhe source of such moisture has been either the wetting of the ashes in the pit, or introduction of a steam-pipe into the ash-pit; but, excepting as a mere experiment, resort is seldom had to such expedients, for the unequal diffusion of the moisture throughout the ash-pit and the difficulty of regulating its proper proportion usually results in extinguishing' the fire on some part of the grate, or proves to be at best of doubtful utility.

Experiments made by me have dem onstrated that by closing the ash-pit and forciby introducing therein,by means of the ordinary fanblowing apparatus, air saturated with the moisture from steam, not only was the energy Specification forming part of Letters Patent No. flfml), dated March l, 1864.

of the combustion increased but a greater quantity of heat from the saine amount of fuel was obtained, less clinker was formed, and when properly applied verylittle or no smoke was produced. Further experiments resulted in the devising of a more simple and useful apparatus, wherewith the air was saturated with the required amount of moisture, and at the same time continuously forced toward and into the fire by means of the direct action of steam upon a column of air. This apparatus, to enable others skilled in the art to make and use,I will describe by reference to the following description thereof, and to the accompanying drawings, making a part of this specification, in which-- Figure 1 is a perspective View of the apparatus complete. Fig.2 is a detached elevation ofthe steam-pipes wiih their perforations toward the observer.

The same letters refer to the same parts in each of the gures.

A A Svc., are a series of pipes perforated with small holes or openings a4 c a, &c,'and connected by any suitable means with a main steam-pipe, B. This series of perforated tubes are affixed within the conical tube or chamber U D at or near its base C with the orifices in the pipes toward the end D. b is the opening in pipe B through which steam from a boiler is allowed to enter. When this apparatus has been connected witlra furnace either by inserting' it in the wall of the ash-pit with the base of the cone outward or in any more convenient position, and a pipe from a steamboiler connected with the main pipe at b, upon closing the door of the ash-pit and then allowing the steam to flow through the orifices a a a, &c., into the tube or chamber .D 2L

continuous current of air will immediately.

enter the tube or chamber C D through the intervals c c', &c., between the perforated pipes A A, Ste., which air is instantly saturated with steam and forced onward and into the iire by the steam from the jets a c a, &c. The greater the pressure of the steam at the jets the greater will be the quantity of steam forced into the fire; and it' the outlet of the furnace remains of the same area the greater will be the pressure in the ash-pit. The tube C D is contracted at its outlet for the purpose of retaining the air and steam in contact for a longer period than would be the case if the tube were of a con stant area; but when,by circumstances, this tube is necessarily prolonged to an extent of three or more diameters, such contraction may be dispensed with without materially affecting the usefulness of the apparatus. The ob` ject ofthe smalloutlets a a. a is to economize the steam, as the draft through the intervals between the pipes depends upon the periphery of the jet and not upon its area, and to furnish the proper proportion of it to the air. If they are made too large or too numerous in the pipes, too much steam will be supplied in proportion to the air, which will be fatal `to the objects of this invention. I have found in practice that from sixty to eighty holes one thirty-second of an inch in diameter for every square foot of surface at the plane of the tubes in the blower furnished satisfactory results.

It is not necessary that the perforated tubes be arranged as shown in the drawings-viz., as concentric circles-nor is it necessary that the section of the chamber C D be circular, or

between the jets for the admission of air and a chamber between the jet-plane and the point where the moist air is delivered, the jets can be arranged in such form as fancy or circumstances may dictate, while the chamber C D must conform in section to the arrangement of the jets. A rectangular section of chamber and the pipes disposed in parallel lines is a good form for general practice. In some cases 1t may be useful to have the axis of thetubes parallel with that of the chamber and the perforations in the ends instead of the side.

When this apparatus is used for ventilation, the foul air must of course be drawn into the blower and then discharged therefrom into the open air, or otherwise disposed of.

The principle upon which this apparatus acts is as follows: The steam as it issues from the several jets driveslv forward all the air immediately in front of them, while the air which surrounds the jets partially condenses the steam, and `in return is expanded by the heat and then thrown forward loaded with moisture bythe succeeding steam, leaving a partial vaccum, into which, the momentum of the steam being too great before condensation to allow it to deviate from its course, the external air rushes from between the pipes to be in turn expanded and driven forward. The hotter the steam the greater will be the amount of `the, vacuum, and consequently the more rapid will be the rush of the external 'air to fill it, while the greater the pressure of the steam the greater will be the pressure in the ash-pit.

The theory of the more perfect combustion which I have found invariably to result from the proper use of this apparatus in practice I will attempt to give, premising `that a more a portion of the ascending acid, converting its into carbonio oxide, which, combining with the undecomposed air which has passed upward through'the fuel, is again converted into acid. i

By properly proportionin g the relative quantities of air and moisture nearly perfecteombus'tion and consequent economy o f y fuel can be obtained.

Having thus fully described my invention, I will again call attention to the essential dif ference between this invention `and those which have been made by others for a similar purpose.

In all previous methods of applying steam to fire the steam has been admittedlinto the ash-pit from a pipe, to the area of the outlet of l which little or no attention has been paid;

andwhere such pipe has been perforated for the purpose of more equallydistributing the` steam in the pit no provision has been madey whereby the fresh air, on entering the pit, could have immediate and free access to each and all ofthe jets. The consequence of this neglect has been that while one portion of the fire was supplied with the proper amount of3 steam and air another part has a surplus of steam and the remainder no steam atall. Again, there has been no plan heretofore adopted whereby the steam should be thoroughly mixed with the air previous to its being allowed to enter the ash-pit, nor has such mixture been supposed necessary. Now, in

this invention the steam is equally distributed over the area of the entrance of a chamber `in numerous small jets instead of pipes of comparatively large area, and each of these jets l isso placed that the surface of the issuing steam is in contact with the entering air."` (A perforated disk similar to the rose of a watering-pot will not answer the purpose, for the air `cannothave free access to the more central i jets.) Finally, the airand steam must be and is thoroughly'mixed before it is allowed to enter the space below the fire. l Having thus describedmy improvements, I,` shall state my claims as follows: A"

I do `not claim the mere introduction of steam into the open lash-pit of la furnace,-'or" into pipes through which air is being supplied ,i to the fire when such steam is allowed to mix simultaneously with the air; nor do I claim" nited fuel in furnaces, Svc., when the said air and steam are mixed in a separate vessel and introduced into a closed ash-pit below the firean apparatus consisting of a single constant steam-jet or of two intermittent steam-jets similar to those frequently employed in a chamber.

chimney for the purpose of increasing the draft ofa furnace; but JOHN T HANCOCK' What I do claim as my invention is- Witnesses:

Supplying commingled air and steam to ig- JOSEPH GAVETT,

ALBERT W. BROWN. 

